本系列文章将展示ElasticSearch中23种非常有用的查询使用方法。由于篇幅原因，本系列文章分为六篇，本文是此系列的第五篇文章。欢迎关注大数据技术博客微信公共账号:iteblog_hadoop。

Filtered Query(过滤查询)

过滤查询允许我们对查询结果进行筛选。比如：我们查询标题和摘要中包含Elasticsearch关键字的图书，但是我们想过滤出评论大于20的结果，可以如下使用：

/////////////////////////////////////////////////////////////////////
 User: 过往记忆
 Date: 2016-10-01
 Time: 23:36
 bolg: https://www.iteblog.com
 本文地址：https://www.iteblog.com/archives/1779.html
 过往记忆博客，专注于hadoop、hive、spark、shark、flume的技术博客，大量的干货
 过往记忆博客微信公共帐号：iteblog_hadoop
/////////////////////////////////////////////////////////////////////
curl POST https://www.iteblog.com:9200/iteblog_book_index/book/_search
{
    "query": {
        "filtered": {
            "query" : {
                "multi_match": {
                    "query": "elasticsearch",
                    "fields": ["title","summary"]
                }
            },
            "filter": {
                "range" : {
                    "num_reviews": {
                        "gte": 20
                    }
                }
            }
        }
    },
    "_source" : ["title","summary","publisher", "num_reviews"]
}

[返回结果]

{
    "took": 20, 
    "timed_out": false, 
    "_shards": {
        "total": 1, 
        "successful": 1, 
        "failed": 0
    }, 
    "hits": [
        {
            "_index": "bookdb_index", 
            "_type": "book", 
            "_id": "1", 
            "_score": 0.5955761, 
            "_source": {
                "summary": "A distibuted real-time search and analytics engine", 
                "publisher": "oreilly", 
                "num_reviews": 20, 
                "title": "Elasticsearch: The Definitive Guide"
            }
        }
    ]
}

注意：过滤查询(Filtered queries)并不强制过滤条件中指定查询。如果没有指定查询条件，则会运行match_all查询，其将会返回index中所有文档，然后对其进行过滤。在实际运用中，过滤器应该先被执行，这样可以减少需要查询的范围。而且，第一次使用fliter之后其将会被缓存，这样会对性能代理提升。

curl POST https://www.iteblog.com:9200/iteblog_book_index/book/_search
{
    "query": {
        "bool": {
            "must" : {
                "multi_match": {
                    "query": "elasticsearch",
                    "fields": ["title","summary"]
                }
            },
            "filter": {
                "range" : {
                    "num_reviews": {
                        "gte": 20
                    }
                }
            }
        }
    },
    "_source" : ["title","summary","publisher", "num_reviews"]
}

这个例子这也适用于下面的多个过滤器例子。

Multiple Filters(多过滤器查询)

多过滤器查询可以通过结合使用bool过滤查询实现。下面的示例中，我们将筛选出返回的结果必须至少有20条评论，必须是在2015年之前发布的，而且应该是由O'Reilly出版的，如下所示：

/////////////////////////////////////////////////////////////////////
 User: 过往记忆
 Date: 2016-10-01
 Time: 23:36
 bolg: https://www.iteblog.com
 本文地址：https://www.iteblog.com/archives/1779.html
 过往记忆博客，专注于hadoop、hive、spark、shark、flume的技术博客，大量的干货
 过往记忆博客微信公共帐号：iteblog_hadoop
/////////////////////////////////////////////////////////////////////
curl POST https://www.iteblog.com:9200/iteblog_book_index/book/_search
{
    "query": {
        "filtered": {
            "query" : {
                "multi_match": {
                    "query": "elasticsearch",
                    "fields": ["title","summary"]
                }
            },
            "filter": {
                "bool": {
                    "must": {
                        "range" : { "num_reviews": { "gte": 20 } }
                    },
                    "must_not": {
                        "range" : { "publish_date": { "lte": "2014-12-31" } }
                    },
                    "should": {
                        "term": { "publisher": "oreilly" }
                    }
                }
            }
        }
    },
    "_source" : ["title","summary","publisher", "num_reviews", "publish_date"]
}

[返回结果]

{
    "took": 21, 
    "timed_out": false, 
    "_shards": {
        "total": 1, 
        "successful": 1, 
        "failed": 0
    }, 
    "hits": [
        {
            "_index": "bookdb_index", 
            "_type": "book", 
            "_id": "1", 
            "_score": 0.5955761, 
            "_source": {
                "summary": "A distibuted real-time search and analytics engine", 
                "publisher": "oreilly", 
                "num_reviews": 20, 
                "title": "Elasticsearch: The Definitive Guide", 
                "publish_date": "2015-02-07"
            }
        }
    ]
}